GONE FISH It's not a good time to be an aquatic vertebrate, real or represented. The precarious state of the Patagonian toothfish, left, one of the top two species in Antarctica, was the leading topic at a conference on the southernmost continent, attended by ministers from 24 countries. At least 20,000 tons of toothfish are illegally netted every year. Even more endangered is the CatDog, right. A federal judge ruled this Nabisco cracker--part of a Nickelodeon tie-in--cannot swim into stores because it looks too much like Pepperidge Farm's famous Goldfish. A Nabisco spokesman called the ruling "fishy." Deep, very deep.